Generally, in the automotive field, especially with regard to trucks, indicator lamp assemblies are employed as to indicate, by their respective energization, that certain selected functions or vehicular operating parameters are in an unacceptable condition. For example, as in a truck, such indicator lamp assemblies may be operatively connected to related sender units which are, in turn, responsive to indicia of engine oil level, engine temperature, loss of engine coolant, generator or alternator output level, actuation or operation of anti-skid mechanism, air pressure in truck air tanks, headlamp selection (whether high or low beam), or parking brake engagement.
Since trucks represent a comparatively high financial investment and since the only way that a profitable return of such investment can be assured is to keep such trucks in use for as long as possible with as little "down-time" (the time during which the truck is taken out of productive use such as, for example, maintenance or inspection) as possible, great care is taken to prevent operation of a truck when all important conditions of such truck are not judged to be up to standard as well as to achieve engine shut-down as quickly as possible after the occurrence of a related failure. Such may occur merely as, for example, prevention of damage to the engine or as a safety measure as, for example, a progressive loss of air pressure in a truck employing pneumatically actuated brakes.
The truck industry has, heretofore, employed one or more indicator lamp assemblies to thereby create, upon energization thereof, a visual signal to the operator that a particular parameter is experiencing less than satisfactory conditions thereby enabling the operator or driver to take corrective action.
Usually a plurality of such indicator lamp assemblies are employed and mounted as on the instrument panel. Further, provision is often made so that upon the operator turning the ignition key toward the engine cranking or "start" position, all of the electrical circuits leading to the indicator lamp assemblies are closed thereby causing energization of the lamp assemblies. It is at this time that the operator can see whether all of the lamp assemblies are still functioning or if any bulb replacement is required.
However, various problems have arisen because of the prior art indicator lamp assemblies. For example, certain of the prior art indicator lamp assemblies employ bulbs of a shank length different from the shank length of bulbs employed in other prior art indicator lamp assemblies. This means that in order to provide for all contingencies, the various truck service centers, as well as the truck operator, must carry a supply of all sizes of bulbs since it is possible that bulbs of differing shank sizes will have to be replaced. Obviously, times occur when the particular size of bulb is not available and because of the reluctance of the operator to operate the truck without being assured that the particular related sensed condition is acceptable, addition "down-time" is created in order to properly inspect the related structure.
Further, since non-energization of an indicator lamp assembly can occur for reasons other than bulb failure, additional problems have been experienced with the prior art indicator lamp assemblies. That is, such non-energization can be the result of a failure within the bulb socket assembly or the electrical conductors leading from the socket assembly to the related source of electrical potential. Because the prior art employed various designs of socket assemblies and because a particular truck instrument panel was effective to receive only one particular design of socket assembly it has heretofore been necessary that truck service centers (often referred to as "truck stops") maintain a large inventory in order to be able to provide whatever design of socket assembly may be required by any particular truck having that need.
The prior art indicator lamp assemblies have created additional problems also resulting in increased costs. For example, generally it is well known that for various reasons it is desirable to make the cab portion (that part of the truck providing space for the operator and associated controls and instruments) as short in length as possible while still providing adequate space for the operator. Consequently, the space as between the instrument panel and, for example, the forward wall of the cab portion is kept at an absolute minimum with such space being filled with as much related operating equipment, controls, linkages and electrical conductors as in practicably possible.
Because of this compactness of construction of the cab it becomes difficult not only to service, for example, the replacement of bulbs which have failed in the indicator lamp assemblies but also in the actual construction of the cab by the truck builder. That is, almost exclusively the prior art indicator lamp assemblies are such as to require the removal and replacement of the bulb from the rear or underside of the instrument panel and, as already stated, such space is usually very limited.
Generally, the builders of trucks in their manufacturing procedures, more specifically, during assembly of the instrument panel and the subsequent assembling of the completed instrument panel to the cab, require that the indicator lamp assemblies be first assembled to the instrument panel, as to comprise a portion of the completed instrument panel before such completed instrument panel is assembled to the cab. This enables the instrument panel to be completed as at a station which is not part of the final assembly of the vehicle.
According to the prior art, the lamp assemblies were thusly assembled. However, because such prior art lamp assemblies were, in the main, constructed of a body-like bulb socket with male type blade terminals carried directly thereby, the assembly of the completed instrument panel onto the cab required the use of intermediate wire harness assemblies which would at one end plug into or onto the blade terminals of the lamp assemblies and, at the other end, plug into terminal ends of vehicular wiring system which could take the form of a second wiring harness. This meant that not only was the final assembly doubly difficult because of the requirement that each lamp assembly had to have two electrical connections made in order to complete a wiring system thereto, but also the fact that two such terminal sets were used for each lamp assembly doubled the possibility of failure at such terminal points. Also, because of the very small space behind or below the instrument panel, it is difficult to assure that proper connections are made to the prior art socket assembly because the terminals thereof are situated relatively closely to the rear or under surface of the instrument panel.
Other problems also exist with respect to the prior art. For example, prior art indicator lamp assemblies often have a lens which is screwed onto the body of the lamp assembly As is apparent, because of the thread lead, it becomes impossible to both tighten the lens onto the body and at the same time be assured that the lens will assume a particular desired position so that any words (such as, for example, "HOT", "OIL", "AIR") formed on such lens are easily readable by the operator. With such prior art lamp assemblies, the lens would have to be tightened and then the lamp body-like socket assembly would have to be turned or rotated until the lens was in a proper attitude at which point the securing means would be tightened. Such time-consuming operations did not totally correct the problem because even after the lens and body-like socket assembly are initially properly secured, the vibrations caused during truck use and consequently experienced by the prior art lamp assembly usually results in the lens becoming loosened as well as the body-like socket assembly rotating within its cooperating mounting aperture in the instrument panel. As is apparent, such vibrations cause misalignment of the prior art lenses.
Accordingly, the invention as herein disclosed and described is primarily directed to the solution of the above as well as other related problems.